In mass production and assembly operations using a power tool, such as a driver, for automatically driving articles having a head and a shank, such as bolts and screws, it is necessary to rapidly supply to the power driver, one article at a time in a predetermined orientation. Usually, although not necessarily, the articles are oriented in generally parallel side-by-side relationship with the heads of adjacent articles abutting each other and their shanks depending in generally parallel relationship. Because they have so many edges, such articles are highly susceptible to becoming caught, hung up, jammed or misaligned and, hence, it is extremely difficult to rapidly and automatically correctly orient and feed such articles to provide an uninterrupted succession of articles with the same desired orientation.
Moreover, the difficulty of properly orienting and feeding these articles is greatly increased whenever the distribution of their mass is such that their centers of gravity or balance along the longitudinal axis lies within or immediately adjacent the head rather than along the shank of the articles. Such articles are in effect head heavy or top heavy and hence very unstable and have an increased tendency to jam, hang up or come to rest on their head with their shank projecting generally upwardly. Usually, top heavy articles have a relatively short shank.
While many devices have been devised for rapidly orienting and feeding such articles, most have proved to be unsatisfactory. However, one device which has been satisfactory for most applications and commercially successful is disclosed and claimed in U.S. Pat. No. 4,436,197. To properly orient articles supplied by an elevator from a hopper, this device utilizes an article gate associated with a pivoted track section which is periodically moved, to dump or remove by gravity improperly oriented articles from the track.
While this device is generally satisfactory it is rather complex, has a limited maximum rate at which it can produce properly oriented articles, and experiences some difficulty in orienting head heavy articles which further limits its maximum rate of producing properly oriented head heavy articles.